JP2021117315A - Projection optical system and projector - Google Patents

Abstract

To provide a projection optical system capable of reducing a projection distance.SOLUTION: A projection optical system 3A comprises a first optical system 31 and a second optical system 32 in order from a reduction side to an enlargement side. The second optical system 32 includes an optical element 33 having a transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in order from the reduction side to the enlargement side. The second reflection surface 36 has a concave shape. A second optical axis N2 of the second reflection surface 36 intersects with a first optical axis N1 of the first optical system 31.SELECTED DRAWING: Figure 3

Description

The present invention relates to a projection optical system and a projector.

Patent Document 1 describes a projector that magnifies and projects a projected image formed by an image forming unit by a projection optical system. The projection optical system of the same document includes a first optical system and a second optical system in this order from the reduction side to the enlargement side. The first optical system includes a refraction optical system including a plurality of lenses. The second optical system consists of a reflection mirror having a concave reflecting surface. The image forming unit includes a light source and a light bulb. The image forming unit forms a projected image on the reduced image plane of the projection optical system. The projection optical system forms an intermediate image between the first optical system and the reflecting surface, and projects the final image on a screen arranged on the magnifying side imaging surface.

Japanese Unexamined Patent Publication No. 2010-20344

The projection optical system and the projector are required to shorten the projection distance.

In order to solve the above problems, the present invention relates to a projection optical system including a first optical system and a second optical system in order from the reduction side to the enlargement side. An optical element having a first transmission surface, a first reflection surface, a second reflection surface, and a second transmission surface is provided in this order from the reduction side to the expansion side, and the second reflection surface has a concave shape. The feature is that the second optical axis of the second reflecting surface intersects the first optical axis of the first optical system.

Next, the projector of the present invention is characterized by having the above-mentioned projection optical system and an image forming unit that forms a projected image on the reduced image plane of the projection optical system.

It is a schematic block diagram of a projector provided with a projection optical system. It is a ray diagram which shows typically the whole of the projection optical system of Example 1. FIG. It is a ray diagram of the projection optical system of Example 1. It is a ray diagram of the 2nd optical system of the projection optical system of Example 1. FIG. It is a perspective view of the optical element of the projection optical system of Example 1. FIG. It is explanatory drawing which shows typically the optical axis of the projection optical system of Example 1. FIG. It is a figure which shows the MTF of the enlargement side of the projection optical system of Example 1. FIG. It is a spot diagram of the projection optical system of Example 1. It is a ray diagram which shows typically the whole of the projection optical system of Example 2. It is a ray diagram of the projection optical system of Example 2. It is a ray diagram when the projection optical system of Example 2 is seen from above. It is a perspective view of the optical element of the projection optical system of Example 2. FIG. It is explanatory drawing which shows typically the optical axis of the projection optical system of Example 2. It is a figure which shows the MTF of the enlargement side of the projection optical system of Example 2. It is a spot diagram of the projection optical system of Example 2. It is a ray diagram which shows typically the whole of the projection optical system of Example 3. It is a ray diagram of the projection optical system of Example 3. It is explanatory drawing which shows typically the optical axis of the projection optical system of Example 3. FIG. It is a figure which shows the MTF of the enlargement side of the projection optical system of Example 3. FIG. It is a spot diagram of the projection optical system of Example 3. It is a ray diagram which shows typically the whole of the projection optical system of Example 4. It is a ray diagram of the projection optical system of Example 4. It is explanatory drawing which shows typically the optical axis of the projection optical system of Example 4. It is a figure which shows the MTF of the enlargement side of the projection optical system of Example 4. It is a spot diagram of the projection optical system of Example 4. It is a ray diagram which shows typically the whole of the projection optical system of Example 5. It is a ray diagram of the projection optical system of Example 5. It is explanatory drawing which shows typically the optical axis of the projection optical system of Example 5. It is a figure which shows the MTF of the enlargement side of the projection optical system of Example 5. It is a spot diagram of the projection optical system of Example 5. It is a ray diagram which shows typically the whole of the projection optical system of Example 6. It is a ray diagram of the projection optical system of Example 6. It is explanatory drawing which shows typically the optical axis of the projection optical system of Example 6. It is a figure which shows the MTF of the enlargement side of the projection optical system of Example 6. It is a spot diagram of the projection optical system of Example 6.

The projection optical system according to the embodiment of the present invention and the projector provided with the projection optical system will be described in detail with reference to the drawings below.

(projector)
FIG. 1 is a schematic configuration diagram of a projector including the projection optical system 3 of the present invention. As shown in FIG. 1, the projector 1 includes an image forming unit 2 that generates a projected image projected on the screen S, a projection optical system 3 that enlarges the projected image and projects an enlarged image on the screen S, and an image forming unit. It includes a control unit 4 that controls the operation of 2.

(Image generation optical system and control unit)
The image forming unit 2 includes a light source 10, a first integrator lens 11, a second integrator lens 12, a polarization conversion element 13, and a superposed lens 14. The light source 10 is composed of, for example, an ultra-high pressure mercury lamp, a solid-state light source, or the like. The first integrator lens 11 and the second integrator lens 12 each have a plurality of lens elements arranged in an array. The first integrator lens 11 divides the light flux from the light source 10 into a plurality of parts. Each lens element of the first integrator lens 11 collects the light flux from the light source 10 in the vicinity of each lens element of the second integrator lens 12.

The polarization conversion element 13 converts the light from the second integrator lens 12 into predetermined linearly polarized light. The superimposing lens 14 superimposes an image of each lens element of the first integrator lens 11 on the display areas of the liquid crystal panel 18R, the liquid crystal panel 18G, and the liquid crystal panel 18B, which will be described later, via the second integrator lens 12.

Further, the image forming unit 2 includes a first dichroic mirror 15, a reflection mirror 16, a field lens 17R, and a liquid crystal panel 18R. The first dichroic mirror 15 reflects R light which is a part of the light rays incident from the superimposing lens 14 and transmits G light and B light which are a part of the light rays incident from the superimposing lens 14. The R light reflected by the first dichroic mirror 15 enters the liquid crystal panel 18R via the reflection mirror 16 and the field lens 17R. The liquid crystal panel 18R is a light modulation element. The liquid crystal panel 18R forms a red projected image by modulating the R light according to the image signal.

Further, the image forming unit 2 includes a second dichroic mirror 21, a field lens 17G, and a liquid crystal panel 18G. The second dichroic mirror 21 reflects G light which is a part of the light beam from the first dichroic mirror 15 and transmits B light which is a part of the light ray from the first dichroic mirror 15. The G light reflected by the second dichroic mirror 21 passes through the field lens 17G and is incident on the liquid crystal panel 18G. The liquid crystal panel 18G is a light modulation element. The liquid crystal panel 18G forms a green projected image by modulating G light according to an image signal.

Further, the image forming unit 2 includes a relay lens 22, a reflection mirror 23, a relay lens 24, a reflection mirror 25, a field lens 17B, and a liquid crystal panel 18B. The B light transmitted through the second dichroic mirror 21 enters the liquid crystal panel 18B via the relay lens 22, the reflection mirror 23, the relay lens 24, the reflection mirror 25, and the field lens 17B. The liquid crystal panel 18B is a light modulation element. The liquid crystal panel 18B forms a blue projected image by modulating the B light according to the image signal.

The liquid crystal panel 18R, the liquid crystal panel 18G, and the liquid crystal panel 18B surround the cross dichroic prism 19 from three directions. The cross dichroic prism 19 is a prism for photosynthesis, and generates a projected image obtained by synthesizing the light modulated by each of the liquid crystal panels 18R, 18G, and 18B.

Here, the cross dichroic prism 19 constitutes a part of the projection optical system 3. The projection optical system 3 magnifies and projects a projected image (an image formed by each of the liquid crystal panels 18R, 18G, and 18B) synthesized by the cross dichroic prism 19 on the screen S. The screen S is an image plane on the enlarged side of the projection optical system 3.

The control unit 4 drives the liquid crystal panel 18R, the liquid crystal panel 18G, and the liquid crystal panel 18B based on the image processing unit 6 to which an external image signal such as a video signal is input and the image signal output from the image processing unit 6. A drive unit 7 is provided.

The image processing unit 6 converts an image signal input from an external device into an image signal including tones of each color. The display drive unit 7 operates the liquid crystal panel 18R, the liquid crystal panel 18G, and the liquid crystal panel 18B based on the projected image signals of each color output from the image processing unit 6. As a result, the image processing unit 6 displays the projected image corresponding to the image signal on the liquid crystal panel 18R, the liquid crystal panel 18G, and the liquid crystal panel 18B.

(Projection optical system)
Hereinafter, as an example of the projection optical system 3 mounted on the projector 1, the projection optical system 3A of the first embodiment and the projection optical system 3B of the second embodiment will be described. In the following description and figures, the liquid crystal panel 18R, the liquid crystal panel 18G, and the liquid crystal panel 18B are represented as the liquid crystal panel 18.

(Example 1)
FIG. 2 is a ray diagram schematically showing the entire projection optical system 3A of the first embodiment. FIG. 3 is a ray diagram of the projection optical system 3A of the first embodiment. FIG. 4 is a ray diagram of the second optical system of the projection optical system 3A of the first embodiment. In FIGS. 2, 3 and 4, the contours of the optical elements constituting the second optical system are omitted. FIG. 5 is a perspective view of the optical element. FIG. 6 is an explanatory diagram schematically showing the optical axis of the projection optical system 3A from the reduction side image plane to the enlargement side image plane.

As shown in FIG. 3, the projection optical system 3A of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side. The first optical system 31 is a refraction optical system including a plurality of lenses L1 to L14. The second optical system 32 includes one optical element 33. As shown in FIGS. 4 and 5, the optical element 33 covers the first transmission surface 34, the first reflection surface 35, the second reflection surface 36, and the second transmission surface 37 in this order from the reduction side to the enlargement side. Have. The first transmission surface 34 has a convex shape protruding toward the reduction side. The second reflecting surface 36 has a concave shape. The first reflecting surface 35 is a flat surface. That is, the first reflecting surface 35 is a plane mirror. The second reflecting surface 36 has a concave shape. The second transmission surface 37 has a convex shape that protrudes toward the enlarged side. The optical element 33 is arranged on the first optical axis N1 of the first optical system 31. In the second optical system 32, the second optical axis N2 of the second reflecting surface 36 intersects the first optical axis N1. As shown in FIG. 4, in this example, the angle θ1 at which the first optical axis N1 and the second optical axis N2 intersect is 90 °.

As shown in FIG. 3, the liquid crystal panel 18 of the image forming unit 2 is arranged on the reduced image plane of the projection optical system 3A. The liquid crystal panel 18 forms a projected image on one side of the first optical axis N1 of the first optical system 31. As shown in FIG. 2, the screen S is arranged on the magnifying side imaging surface of the projection optical system 3A. The final image is projected on the screen S. The screen S is located on the side opposite to the projected image of the liquid crystal panel 18 with respect to the first optical axis N1. As shown in FIG. 4, between the first optical system 31 and the second reflecting surface 36 of the optical element 33, an intermediate image 40 conjugated with the reduction side image plane and the enlargement side image plane is formed. .. The intermediate image 40 is a conjugated image that is upside down with respect to the final image. In this example, the intermediate image 40 is formed inside the optical element 33. More specifically, the intermediate image 40 is formed between the first reflecting surface 35 and the second reflecting surface 36.

In the following description, for convenience, the three axes orthogonal to each other will be referred to as the X-axis, the Y-axis, and the Z-axis. Further, the width direction of the screen S, which is the image plane on the enlarged side, is the X-axis direction, the vertical direction of the screen S is the Y-axis direction, and the direction perpendicular to the screen S is the Z-axis direction. The side where the screen S is located in the Z-axis direction is referred to as the first direction Z1, and the opposite side is referred to as the second direction Z2. Further, a plane extending in the Y-axis direction including the second optical axis N2 of the second reflecting surface 36 of the optical element 33 is defined as a YZ plane. 2, FIG. 3 and FIG. 4 are ray diagrams on the YZ plane, respectively.

As shown in FIG. 3, in this example, the first optical axis N1 of the first optical system 31 extends in the Y-axis direction. The second optical axis N2 of the second optical system 32 extends in the Z-axis direction. The liquid crystal panel 18 forms a projected image in the first direction Z1 of the first optical axis N1 of the first optical system 31.

As shown in FIG. 3, the first optical system 31 includes a cross dichroic prism 19 and 14 lenses L1 to L14. The lenses L1 to L14 are arranged in this order from the reduction side to the enlargement side. In this example, the lens L2 and the lens L3 are the first bonded lenses L21 that are joined. The lens L4 and the lens L5 are a bonded second bonded lens L22. The lens L9 and the lens L10 are a bonded third junction lens L23. The lens L11 and the lens L12 are a bonded fourth junction lens L24. A diaphragm (not shown) is arranged between the lens L7 and the lens L8.

Here, in the first optical system 31, the lens L13 has a positive power. Further, the first optical system 31 has positive power as a whole. Therefore, as shown in FIG. 3, between the first optical system 31 and the second optical system 32, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32.

The optical element 33 is designed with the second optical axis N2 of the second reflecting surface 36 as a design axis. In other words, the second optical axis N2 is the design optical axis of the second transmitting surface 37 and the second reflecting surface 36. As shown in FIG. 4, the first transmission surface 34, the first reflection surface 35, and the second reflection surface 36 are located below Y2 of the second optical axis N2, and the second transmission surface 37 is the second optical axis. It is located above Y1 of N2. Further, the first transmission surface 34, the first reflection surface 35, and the second transmission surface 37 are located in the first direction Z1 with respect to the first optical axis N1, and the second reflection surface 36 is from the first optical axis N1. Is also located in the second direction Z2. The intermediate image 40 is located below Y2 of the second optical axis N2.

In this example, as shown in FIG. 5, the second reflecting surface 36 and the second transmitting surface 37 of the optical element 33 have a rotationally symmetric shape centered on the second optical axis N2. The second reflecting surface 36 and the second transmitting surface 37 are each provided in an angle range of 180 ° about the second optical axis N2. The first transmission surface 34 is designed with the first optical axis N1 as a design axis. The first transmission surface 34 has a rotationally symmetric shape centered on the first optical axis N1. The first transmission surface 34 is provided in an angle range of 180 ° about the first optical axis N1.

The first transmission surface 34, the second reflection surface 36, and the second transmission surface 37 of the optical element 33 are all aspherical surfaces. The first reflective surface 35 and the second reflective surface 36 are reflective coating layers provided on the outer surface of the optical element 33. Each of the first transmission surface 34, the second reflection surface 36, and the second transmission surface 37 may be a free curved surface. In this case, each free-form surface is designed based on its own design axis. In this case, when the second reflecting surface is a free curved surface, the design axis of the second reflecting surface is referred to as the second optical axis N2.

As shown by the arrow of the chain line in FIG. 5, the first reflecting surface 35 reflects the light flux passing through the first transmitting surface 34 in the direction intersecting the first optical axis N1. In this example, the first reflecting surface 35 bends the light flux passing through the first transmitting surface 34 by 90 ° in the second direction Z2 away from the screen S. The light flux reflected by the first reflecting surface 35 is reflected upward Y1 by the second reflecting surface 36 in the first direction Z1 toward the screen S. The luminous flux reflected by the second reflecting surface 36 and passing through the second transmitting surface 37 is emitted from the optical element 33 in the Y1 direction and reaches the screen S.

Here, as shown in FIG. 6, in the projection optical system 3A, the reduction side image plane intersects the enlargement side image plane. That is, the enlarged side reduced image plane on which the liquid crystal panel 18 forms the projected image is along the XZ plane. The longitudinal direction of the liquid crystal panel 18, that is, the width direction W1 of the projected image extends in the X-axis direction. The lateral direction of the liquid crystal panel 18, that is, the height direction H1 of the projected image extends in the Z-axis direction. The screen S on which the final image is formed is along the XY plane. The longitudinal direction of the screen S, that is, the width direction W2 of the final image extends in the X-axis direction. The lateral direction of the screen S, that is, the height direction H2 of the final image extends in the Y-axis direction.

(Lens data)
The lens data of the projection optical system 3A is as follows. The surface numbers are assigned in order from the enlargement side to the reduction side. For aspherical surfaces, * is attached to the surface number. The code is a code attached to each configuration of the projection optical system. r is the radius of curvature. d is the shaft upper surface spacing. nd is the refractive index. vd is an Abbe number. Y is the effective radius. The unit of r, d, and Y is mm. The projection distance of the projection optical system 3A is the distance from the surface number 31 which is the second transmission surface 37 to the screen S.

Surface number Name rd nd vd Mode Y
Object surface 18 0 8.5 Refraction
1 19 0 35.95 1.51633 64.14 Refraction 12.573
2 0 5 Refraction 14.999
3 L01 29.33178 10.078656 1.442044 86.63 Refraction 16
4 -46.7571 0.1 Refraction 15.852
5 L02 148.79233 7.071831 1.772054 47.71 Refraction 14.902
6 L03 -26.54503 6.108227 2.0196 20.783 Refraction 14.521
7 -95.30317 0.1 Refraction 13.827
8 L04 57.12601 5.870101 1.494958 52.92 Refraction 12.989
9 L05 -24.31043 1 2.0508 26.942 Refraction 12.77
10 -887.31514 0.2 Refraction 12.691
11 L06 37.22942 2.436591 1.986125 16.48 Refraction 12.565
12 155.01669 2.483493 Refraction 12.414
13 L07 -45.82387 8.6095 1.526239 38.78 Refraction 12.314
14 -32.53128 9.5 Refraction 11.559
Aperture surface 0 0.1 Refraction 7.5
16 L08 -323.72495 2 2.0508 26.942 Refraction 7.5
17 42.89214 1.15812 Refraction 7.578
18 L09 1757.31503 4.943349 1.840029 18.61 Refraction 7.709
19 L10 -12.35292 2 2.0508 26.942 Refraction 7.982
20 -48.32828 28.476179 Refraction 8.812
21 L11 45.45967 15 1.686174 23.14 Refraction 19
22 L12 -29.191 12.671948 1.990031 16.9 Refraction 19.076
23 -3485.13836 4.481986 Refraction 21.906
* 24 L13 105.64407 6 1.531131 55.75 Refraction 22.487
* 25 -519.77235 24.526951 Refraction 23.721
* 26 L14 -78.70625 6 1.531131 55.75 Refraction 27.151
* 27 66.20602 2.620232 Refraction 30.053
* 28 34 57.65154 47 1.509398 56.47 Refraction 30.974
29 35 0 -18 1.509398 56.47 Reflection 41.343
* 30 36 17.73917 40 1.509398 56.47 Reflection 20.636
* 31 37 -60 286 Refraction 37.407
Image plane S 0 0 Refraction 1897.748

The surface number 29, that is, the decenter & bend of the first reflecting surface 35 is α = −45. The aspherical coefficients of each aspherical surface are as follows.

Face number 24
Conic constant 5.747129E + 00
Fourth-order coefficient -1.773701E-05
6th order coefficient 2.099464E-08
8th order coefficient -5.487779E-11
10th order coefficient 7.584515E-15
Face number 25
Conic constant -1E + 02
Fourth-order coefficient -1.423867E-05
6th order coefficient 1.409802E-08
8th order coefficient -4.012394E-11
10th order coefficient 8.047043E-15
Face number 26
Conic constant 5.86971E + 00
Fourth-order coefficient -6.931921E-06
6th order coefficient -2.037596E-08
8th order coefficient 2.860225E-11
10th order coefficient -4.032263E-15
Face number 27
Conic constant 5.341384E-01
Fourth-order coefficient -3.273916E-05
6th order coefficient 1.751897E-08
8th order coefficient -7.121867E-12
10th order coefficient 1.654097E-15
Face number 28
Conic constant 1.933343E + 00
Fourth order coefficient 3.63149E-06
6th order coefficient -9.290606E-09
8th order coefficient 1.233337E-11
10th order coefficient -7.387416E-15
Face number 30
Conic constant -3.045767E + 00
Fourth-order coefficient 1.087866E-05
6th order coefficient -3.933264E-08
8th order coefficient 6.851884E-11
10th order coefficient -6.380783E-14
Face number 31
Conic constant 1.393652E + 00
Fourth-order coefficient 1.213214E-06
6th order coefficient -3.767339E-09
8th order coefficient 2.904918E-12
10th order coefficient -9.240926E-16

(Action effect)
The projection optical system 3A of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side. The second optical system 32 includes an optical element 33 having a first transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in this order from the reduction side to the enlargement side. The second reflecting surface 36 has a concave shape. The second optical axis N2 of the second reflecting surface 36 intersects the first optical axis N1 of the first optical system 31.

In this example, in the second optical system 32, the light flux reflected by the second reflecting surface 36 can be refracted by the second transmitting surface 37. Therefore, the projection distance of the projection optical system 3A can be shortened as compared with the case where the second optical system 32 includes only the second reflection surface 36. In other words, the projection optical system 3A of this example can shorten the focus of the projection optical system 3A as compared with the case where the second optical system 32 includes only the second reflection surface 36.

Further, since the projection optical system 3A of this example includes the first reflection surface 35, it is easy to direct the light flux emitted from the second optical system 32 in a direction that does not interfere with the first optical system 31. ..

Further, in this example, since one optical element includes the first reflecting surface 35 and the second reflecting surface 36, the second optical system 32 is smaller than the case where the two reflecting surfaces are provided in separate optical elements. Can be transformed into. Further, since the first reflecting surface 35 and the second reflecting surface 36 can be integrally molded, high-precision molding is possible.

Further, the first optical axis N1 of the first optical system 31 extends in the Y-axis direction on the YZ plane, and the second optical axis N2 of the second optical system 32 extends in the Z-axis direction on the YZ plane. Therefore, the projection optical system 3A is miniaturized in the X-axis direction and the Z-axis direction.

Further, in this example, since the optical element 33 includes the convex second transmission surface 37 protruding toward the enlargement side, it is possible to prevent the second reflection surface 36 arranged on the enlargement side of the intermediate image 40 from becoming large. .. That is, in the second optical system 32, since the light flux can be refracted on the second transmission surface 37, the intermediate image 40 conjugate with the magnifying side imaging surface is greatly inclined along the second optical axis N2. It can be suppressed. Therefore, it is possible to prevent the second reflecting surface 36 located on the enlarged side of the intermediate image 40 from becoming large.

Further, the intermediate image 40 is located between the first reflecting surface 35 and the second reflecting surface 36 of the optical element 33. Therefore, the first optical system 31 and the optical element 33 can be brought closer to each other as compared with the case where the intermediate image 40 is formed between the first optical system 31 and the optical element 33. As a result, the projection optical system 3A can be miniaturized in the Y-axis direction and the Z-axis direction.

Further, in the optical element 33, since the first transmission surface 34 located on the reduction side of the intermediate image 40 is an aspherical surface, it is possible to suppress the occurrence of aberration in the intermediate image 40. Further, the second reflecting surface 36 and the second transmitting surface 37 of the optical element 33 are aspherical surfaces. Therefore, the occurrence of aberration can be suppressed on the magnified image plane.

Further, in the optical element 33, the first transmission surface 34 is a rotationally symmetric surface centered on the first optical axis N1, the second reflection surface 36, and the second transmission surface 37 rotate about the second optical axis N2. It has a symmetrical shape. Therefore, the optical element 33 can be easily manufactured as compared with the case where these surfaces are not rotationally symmetric.

Further, in this example, between the first optical system 31 and the second optical system 32, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32. Therefore, the intermediate image 40 can be easily formed and the intermediate image 40 can be made smaller. Therefore, it is easy to miniaturize the second reflecting surface 36 located on the enlarged side of the intermediate image 40.

FIG. 7 is a diagram showing an MTF on the enlarged side of the projection optical system 3A. The horizontal axis of FIG. 7 showing the MTF is the spatial frequency. The vertical axis is the contrast reproduction ratio. FIG. 8 is a spot diagram showing the state of light collection for each image height position. As shown in FIGS. 7 and 8, the projection optical system 3A has a high resolution.

(Example 2)
FIG. 9 is a ray diagram schematically showing the entire projection optical system 3B of the second embodiment. In FIG. 9, the projection optical system 3B of the second embodiment is viewed from above Y1. FIG. 10 is a light ray diagram when the projection optical system 3B of the second embodiment is viewed from the Z-axis direction perpendicular to the screen S. FIG. 11 is a ray diagram when the projection optical system 3B is viewed from above Y1. 9 and 11 are ray diagrams of an XZ plane extending in the X-axis direction including the second optical axis N2 of the second optical system 32. In FIGS. 9, 10 and 11, the contours of the optical elements 33 constituting the second optical system 32 are omitted. FIG. 12 is a perspective view of the optical element 33 of the second embodiment. FIG. 13 is an explanatory diagram schematically showing the optical axis of the projection optical system 3B from the reduction side image plane to the enlargement side image plane.

As shown in FIGS. 10 and 11, the projection optical system 3B of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side. The first optical system 31 is a refraction optical system including a plurality of lenses L1 to L14. The first optical axis N1 of the first optical system 31 extends in the X-axis direction parallel to the screen S, which is the magnifying image plane.

The second optical system 32 includes one optical element 33. The optical element 33 has a first transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in this order from the reduction side to the enlargement side. The first transmission surface 34 has a convex shape protruding toward the reduction side. The second reflecting surface 36 has a concave shape. The first reflecting surface 35 is a flat surface. That is, the first reflecting surface 35 is a plane mirror. The second reflecting surface 36 has a concave shape. The second transmission surface 37 has a convex shape that protrudes toward the enlarged side. The optical element 33 constituting the second optical system 32 is arranged on the first optical axis N1 of the first optical system 31. In the second optical system 32, the second optical axis N2 of the second reflecting surface 36 intersects the first optical axis N1. As shown in FIG. 11, the angle θ1 at which the first optical axis N1 and the second optical axis N2 intersect is 90 °. The second optical axis N2 extends in the Z-axis direction.

The liquid crystal panel 18 of the image forming unit 2 is arranged on the image plane on the reduced side of the projection optical system 3B. As shown in FIG. 10, the liquid crystal panel 18 forms a projected image on Y1 above the first optical axis N1 of the first optical system 31. As shown in FIG. 9, the screen S is arranged on the magnifying side imaging surface of the projection optical system 3B. The final image is projected on the screen S. The screen S is located above Y1 of the first optical axis N1. As shown in FIG. 10, between the first optical system 31 and the second reflecting surface 36 of the optical element 33, an intermediate image 40 conjugated to the reduction side image plane and the enlargement side image plane is formed. .. The intermediate image 40 is a conjugated image that is upside down with respect to the final image. In this example, the intermediate image 40 is formed inside the optical element 33. More specifically, the intermediate image 40 is formed between the first reflecting surface 35 and the second reflecting surface 36. The intermediate image 40 is located below Y2 of the first optical axis N1.

As shown in FIGS. 10 and 11, the first optical system 31 includes a cross dichroic prism 19 and 14 lenses L1 to L14. The lenses L1 to L14 are arranged in this order from the reduction side to the enlargement side. In this example, the lens L2 and the lens L3 are the first bonded lenses L21 that are joined. The lens L4 and the lens L5 are a bonded second bonded lens L22. The lens L9 and the lens L10 are a bonded third junction lens L23. The lens L11 and the lens L12 are a bonded fourth junction lens L24. A diaphragm (not shown) is arranged between the lens L7 and the lens L8.

Here, in the first optical system 31, the lens L13 has a positive power. Further, the first optical system 31 has positive power as a whole. As a result, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32 between the first optical system 31 and the second optical system 32.

The optical element 33 is designed with the second optical axis N2 of the second reflecting surface 36 as a design axis. In other words, the second optical axis N2 is the design optical axis of the second transmitting surface 37 and the second reflecting surface 36. As shown in FIG. 12, the first transmission surface 34, the first reflection surface 35, and the second reflection surface 36 are located at Y2 below the second optical axis N2. The second transmission surface 37 is located above Y1 of the second optical axis N2. Further, the first transmission surface 34, the first reflection surface 35, and the second transmission surface 37 are located in the first direction Z1 with respect to the first optical axis N1, and the second reflection surface 36 is from the first optical axis N1. Is also located in the second direction Z2. The first reflecting surface 35 and the second reflecting surface 36 face each other in the Z-axis direction.

Further, the first transmission surface 34, the second reflection surface 36, and the second transmission surface 37 of the optical element 33 have a rotationally symmetric shape centered on the second optical axis N2. The first transmitting surface 34, the second reflecting surface 36, and the second transmitting surface 37 are each provided in an angle range of 180 ° about the second optical axis N2.

The first transmission surface 34, the second reflection surface 36, and the second transmission surface 37 of the optical element 33 are all aspherical surfaces. The first reflective surface 35 and the second reflective surface 36 are reflective coating layers provided on the outer surface of the optical element 33. Each of the first transmission surface 34, the second reflection surface 36, and the second transmission surface 37 may be a free curved surface. In this case, the second reflecting surface 36 and the second transmitting surface 37 are designed with the second optical axis N2 as the design axis. Further, the first transmission surface 34 is designed with the first optical axis N1 as a design axis.

As shown by the arrow of the chain line in FIG. 12, the first reflecting surface 35 reflects the light flux passing through the first transmitting surface 34 in the direction intersecting the first optical axis N1. As shown in FIG. 11, the angle θ at which the first reflecting surface 35 refracts the light flux passing through the first transmitting surface 34 in the second direction Z2 away from the screen S is 90 °. The light flux reflected by the first reflecting surface 35 is reflected by the second reflecting surface 36 in the first direction Z1 toward the upper Y1. The luminous flux reflected by the second reflecting surface 36 and passing through the second transmitting surface 37 is emitted from the optical element 33 in the Y1 direction and reaches the screen S.

As shown in FIG. 13, in the projection optical system 3B, the reduction side image plane intersects the enlargement side image plane. That is, the enlarged side reduced image plane on which the liquid crystal panel 18 forms the projected image is along the YZ plane. The longitudinal direction of the liquid crystal panel 18, that is, the width direction W1 of the projected image extends in the Z-axis direction. The lateral direction of the liquid crystal panel 18, that is, the height direction H1 of the projected image extends in the Y-axis direction. The screen S on which the final image is formed is along the XY plane. The longitudinal direction of the screen S, that is, the width direction W2 of the final image extends in the X-axis direction. The lateral direction of the screen S, that is, the height direction H2 of the final image extends in the Y-axis direction.

(Lens data)
The lens data of the projection optical system 3B is as follows. The projection distance of the projection optical system 3B is the distance from the surface number 30 to the screen S.

Surface number Name rd nd vd Mode Y
Object surface 18 0 8.5 Refraction
1 19 0 35.95 1.51633 64.14 Refraction 12.573
2 0 5 Refraction 14.999
3 L01 29.33178 10.078656 1.442044 86.63 Refraction 16
4 -46.7571 0.1 Refraction 15.852
5 L02 148.79233 7.071831 1.772054 47.71 Refraction 14.902
6 L03 -26.54503 6.108227 2.0196 20.783 Refraction 14.521
7 -95.30317 0.1 Refraction 13.827
8 L04 57.12601 5.870101 1.494958 52.92 Refraction 12.989
9 L05 -24.31043 1 2.0508 26.942 Refraction 12.77
10 -887.31514 0.2 Refraction 12.691
11 L06 37.22942 2.436591 1.986125 16.48 Refraction 12.565
12 155.01669 2.483493 Refraction 12.414
13 L07 -45.82387 8.6095 1.526239 38.78 Refraction 12.314
14 -32.53128 9.5 Refraction 11.559
Aperture surface 0 0.1 Refraction 7.5
16 L08 -323.72495 2 2.0508 26.942 Refraction 7.5
17 42.89214 1.15812 Refraction 7.578
18 L09 1757.31503 4.943349 1.840029 18.61 Refraction 7.709
19 L10 -12.35292 2 2.0508 26.942 Refraction 7.982
20 -48.32828 28.476179 Refraction 8.812
21 L11 45.45967 15 1.686174 23.14 Refraction 19
22 L12 -29.191 12.671948 1.990031 16.9 Refraction 19.076
23 -3485.13836 4.481986 Refraction 21.906
* 24 L13 105.64407 6 1.531131 55.75 Refraction 22.487
* 25 -519.77235 24.526951 Refraction 23.721
* 26 L14 -78.70625 6 1.531131 55.75 Refraction 27.151
* 27 66.20602 2.620232 Refraction 30.053
* 28 34 57.65154 37 1.509398 56.47 Refraction 30.974
29 35 0 -28 1.509398 56.47 Reflection 41.343
* 30 36 17.73917 40 1.509398 56.47 Reflection 20.636
* 31 37 -60 286 Refraction 37.407
Image plane S 0 0 Refraction 1897.748

The surface number 29, that is, the decenter & bend of the first reflecting surface 35 is β = −45. The other lens data excluding the value of the distance d between the upper surfaces of the shafts in the column of the surface number 28 and the value of the distance d between the upper surfaces of the shafts in the column of the surface number 29 are the same as those of the projection optical system 3A of the first embodiment. .. Further, the data of the aspherical coefficient of each aspherical surface is also the same as that of the projection optical system 3A of the first embodiment.

(Action effect)
The projection optical system 3B of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side of the first optical system. The second optical system 32 includes an optical element 33 having a first transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in this order from the reduction side to the enlargement side. The second reflecting surface 36 has a concave shape. The second optical axis N2 of the second reflecting surface 36 intersects the first optical axis N1 of the first optical system 31.

In the projection optical system 3B of this example, the light flux reflected by the second reflecting surface 36 in the second optical system 32 can be refracted by the second transmitting surface 37. Therefore, the projection distance of the projection optical system 3B can be shortened as compared with the case where the second optical system 32 includes only the second reflection surface 36. In other words, the projection optical system 3B of this example can shorten the focus of the projection optical system 3B as compared with the case where the second optical system 32 includes only the second reflection surface 36.

Further, since the projection optical system 3B of this example includes the first reflection surface 35, it is easy to direct the light flux emitted from the second optical system 32 in a direction that does not interfere with the first optical system 31. ..

Further, in this example, since one optical element includes the first reflecting surface 35 and the second reflecting surface 36, the second optical system 32 is provided as compared with the case where the two reflecting surfaces are provided on separate optical elements. Can be miniaturized. Further, since the first reflecting surface 35 and the second reflecting surface 36 can be integrally molded, high-precision molding is possible.

Further, the first optical axis N1 of the first optical system 31 extends in the X-axis direction on the XZ plane, and the second optical axis N2 of the second optical system 32 extends in the Z-axis direction on the XZ plane. Therefore, the projection optical system 3B is miniaturized in the Y-axis direction. Also in the Z-axis direction. Since it is bent at the first reflecting surface 35, it is miniaturized in the Z-axis direction.

Further, in this example, since the optical element 33 includes the convex second transmission surface protruding to the enlargement side, it is possible to prevent the second reflection surface 36 arranged on the enlargement side of the intermediate image 40 from becoming large. That is, in the second optical system 32, since the light flux can be refracted on the second transmission surface 37, the intermediate image 40 conjugate with the magnifying side imaging surface is greatly inclined along the second optical axis N2. It can be suppressed. Therefore, it is possible to prevent the second reflecting surface 36 located on the enlarged side of the intermediate image 40 from becoming large.

Further, the intermediate image 40 is located between the first reflecting surface 35 and the second reflecting surface 36 of the optical element 33. Therefore, the first optical system 31 and the optical element 33 can be brought closer to each other as compared with the case where the intermediate image 40 is formed between the first optical system 31 and the optical element 33. As a result, the projection optical system 3B can be miniaturized in the Y-axis direction.

Further, in the optical element 33, since the first transmission surface 34 located on the reduction side of the intermediate image 40 is an aspherical surface, it is possible to suppress the occurrence of aberration in the intermediate image 40. Further, the second reflecting surface 36 and the second transmitting surface 37 of the optical element 33 are aspherical surfaces. Therefore, the occurrence of aberration can be suppressed on the magnified image plane.

Further, in the optical element 33, the first transmission surface 34 has a shape that is rotationally symmetric with respect to the first optical axis N1. Further, the second reflecting surface 36 and the second transmitting surface 37 have a shape that is rotationally symmetric with respect to the second optical axis N2. Therefore, the optical element 33 can be easily manufactured as compared with the case where these surfaces are not rotationally symmetric.

Further, in this example, between the first optical system 31 and the second optical system 32, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32. Therefore, the intermediate image 40 can be easily formed and the intermediate image 40 can be made smaller. Therefore, it is easy to miniaturize the second reflecting surface 36 located on the enlarged side of the intermediate image 40.

FIG. 14 is a diagram showing an MTF on the enlarged side of the projection optical system 3B. FIG. 15 is a spot diagram showing the state of light collection for each image height position. As shown in FIGS. 14 and 15, the projection optical system 3B has a high resolution.

(Example 3)
FIG. 16 is a ray diagram schematically showing the entire projection optical system 3C of the third embodiment. FIG. 17 is a ray diagram of the projection optical system 3C of the third embodiment. In FIGS. 16 and 17, the projection optical system 3C is viewed from the X-axis direction parallel to the screen S. In FIGS. 16 and 17, the contours of the optical elements 33 constituting the second optical system 32 are omitted. FIG. 18 is an explanatory diagram schematically showing the optical axis of the projection optical system 3C from the reduction side image plane to the enlargement side image plane.

In the projection optical system 3C of this example, a deflection element 50 that refracts the first optical axis N1 is arranged in the middle of the first optical system 31 of the projection optical system 3A of the first embodiment. The optical elements 33 of the lenses L1 to L14 and the second optical system 32 are the same as those of the projection optical system 3A.

As shown in FIG. 16, the projection optical system 3C of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side. The first optical system 31 is a refraction optical system including a plurality of lenses L1 to L14 and a deflection element 50. As shown in FIG. 17, the first optical system 31 includes a cross dichroic prism 19 and 14 lenses L1 to L14. The lens L2 and the lens L3 are first bonded lenses L21 that are joined. The lens L4 and the lens L5 are a bonded second bonded lens L22. The lens L9 and the lens L10 are a bonded third junction lens L23. The lens L11 and the lens L12 are a fourth bonded lens that is joined.

The deflection element 50 is a plane mirror. As shown in FIGS. 3, 16 and 17, the deflection element 50 has a first air spacing having the widest distance between the upper surfaces of the shafts among a plurality of air gaps provided between adjacent lenses in the first optical system 31. It is placed in G1. The first air gap G1 is between the lens L10 and the lens L11, that is, between the third junction lens L23 and the fourth junction lens L24. The deflection element 50 is arranged at the first air gap G1 and bends the first optical axis N1 of the first optical system 31. In the first optical system 31, the first portion 51 located on the reduction side of the deflection element 50 includes lenses L1 to L10. In the first optical system 31, the second portion 52 located on the enlargement side of the deflection element 50 includes lenses L11 to L14.

Due to the arrangement of the deflection element 50, the first optical axis portion M1 which is the optical axis of the first part 51 and the second optical axis portion M2 which is the optical axis of the second part 52 intersect. In this example, the angle at which the first optical axis portion M1 and the second optical axis portion M2 intersect is 90 °. In other words, the deflection element 50 is arranged at an angle of 45 ° with respect to the first optical axis N1 of the first optical system 31 before the deflection element 50 is arranged. The first optical axis portion M1 extends in the Z-axis direction, and the second optical axis portion M2 extends in the Y-axis direction. The deflection element 50 bends the light flux emitted from the first portion 51 in the second direction Z2 by 90 ° downward to Y2.

Here, the first part 51 has a positive power. Part 2 52 comprises negative power. Further, the first optical system 31 has positive power as a whole. As a result, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32 between the first optical system 31 and the second optical system 32.

The optical element 33 has a first transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in this order from the reduction side to the enlargement side. The first transmission surface 34 has a convex shape that protrudes toward the reduction side. The first reflecting surface 35 is a flat surface. The second reflecting surface 36 has a concave shape. The second transmission surface 27 has a convex shape that protrudes toward the enlarged side.

A light flux emitted from the first optical system 31 downward Y2 is incident on the first transmission surface 34. The first reflecting surface 35 is bent 90 ° in the second direction Z2 away from the screen S. The light flux reflected by the first reflecting surface 35 is reflected downward Y2 toward the first direction Z1 by the second reflecting surface 36. The light flux reflected by the second reflecting surface 36 and passing through the second transmitting surface 37 is emitted from the optical element 33 downward to Y2 and reaches the screen S.

Here, as shown in FIG. 18, in the projection optical system 3C, the enlargement side image plane and the reduction side image plane are parallel. That is, the magnified image plane on which the liquid crystal panel 18 forms the projected image is along the XY plane. The longitudinal direction of the liquid crystal panel 18, that is, the width direction W1 of the projected image extends in the X-axis direction. The lateral direction of the liquid crystal panel 18, that is, the height direction H1 of the projected image extends in the Y-axis direction. The screen S on which the final image is formed is along the XY plane. The longitudinal direction of the screen S, that is, the width direction W2 of the final image extends in the X-axis direction. The lateral direction of the screen S, that is, the height direction H2 of the final image extends in the Y-axis direction.

(Lens data)
The lens data of the projection optical system 3C is as follows.
Surface number Name rd nd vd Mode Y
Object surface 18 0 8.5 Refraction
1 19 0 35.95 1.51633 64.14 Refraction 12.573
2 0 5 Refraction 14.999
3 L01 29.33178 10.078656 1.442044 86.63 Refraction 16
4 -46.7571 0.1 Refraction 15.852
5 L02 148.79233 7.071831 1.772054 47.71 Refraction 14.902
6 L03 -26.54503 6.108227 2.0196 20.783 Refraction 14.521
7 -95.30317 0.1 Refraction 13.827
8 L04 57.12601 5.870101 1.494958 52.92 Refraction 12.989
9 L05 -24.31043 1 2.0508 26.942 Refraction 12.77
10 -887.31514 0.2 Refraction 12.691
11 L06 37.22942 2.436591 1.986125 16.48 Refraction 12.565
12 155.01669 2.483493 Refraction 12.414
13 L07 -45.82387 8.6095 1.526239 38.78 Refraction 12.314
14 -32.53128 9.5 Refraction 11.559
Aperture surface 0 0.1 Refraction 7.5
16 L08 -323.72495 2 2.0508 26.942 Refraction 7.5
17 42.89214 1.15812 Refraction 7.578
18 L09 1757.31503 4.943349 1.840029 18.61 Refraction 7.709
19 L10 -12.35292 2 2.0508 26.942 Refraction 7.982
20 -48.32828 28.476179 Refraction 8.812
21 51 0 -18 Reflection 24.52
22 L11 -45.45967 -15 1.686174 23.14 Refraction 19
23 L12 29.191 -12.671948 1.990031 16.9 Refraction 19.076
24 3485.13836 -4.481986 Refraction 21.906
* 25 L13 -105.64407 -6 1.531131 55.75 Refraction 22.487
* 26 519.77235 -24.526951 Refraction 23.721
* 27 L14 78.70625 -6 1.531131 55.75 Refraction 27.151
* 28 -66.20602 -2.620232 Refraction 30.053
* 29 34 -57.65154 -47 1.509398 56.47 Refraction 30.974
30 35 0 18 1.509398 56.47 Reflection 41.343
* 31 36 -17.73917 -40 1.509398 56.47 Reflection 20.636
* 32 60 -286 Refraction 37.407
Image plane S 0 0 Refraction 1897.748

The surface number 21 is a reflective surface of the deflection element 50. The surface number 21 decenter & bend is α = 45. The surface number 30, that is, the decenter & bend of the first reflecting surface 35 is α = 45. The aspherical coefficient of each aspherical surface is the same as that of the first embodiment. That is, the aspherical coefficients of the surface numbers 25 to 29 and the surface numbers 31 and 32 are the same as the aspherical coefficients of the surface numbers 24 to 28 and the surface numbers 30 and 31 of the first embodiment.

Further, as can be seen from the lens data, the first length R1 which is the total length of the first part 51 is longer than the second length R2 which is the total length of the second part 52. That is, as shown in FIG. 16, the first length R1 from the liquid crystal panel 18 which is the image plane on the reduction side to the surface on the enlargement side of the lens L10 is from the surface on the reduction side of the lens L11 to the surface on the enlargement side of the lens L14. The second length to the surface is longer than R2. In other words, the second length R2, which is the total length of the second part 52, is shorter than the first length R1 which is the total length of the first part 51. The first length R1 is 113.21 mm and the second length R2 is 68.6809 mm.

(Action effect)
The projection optical system 3C of this example can obtain the same effects as the projection optical system 3A of the first embodiment.

Further, in this example, a deflection element 50 that bends the first optical axis N1 of the first optical system 31 extending in the Z-axis direction downward Y2 is arranged. As a result, the first optical system 31 includes a second portion 52 extending in the Y-axis direction and a first portion 51 extending in the Z-axis direction. Therefore, the projection optical system 3C of this example is larger in the Z-axis direction than the projection optical system 3A of the first embodiment, but can be miniaturized in the Y-axis direction.

Further, in this example, the deflection element 50 is arranged in the first optical system 31 at the first air gap G1 where the distance between the upper surfaces of the shafts on the first optical axis N1 is the widest. Therefore, the deflection element 50 can be easily arranged. Further, even when the deflection element 50 is arranged, it is possible to prevent the first optical system 31 from becoming large.

Further, in this example, in the first optical system 31, the second length R2, which is the total length of the second part 52, is shorter than the first length R1 which is the total length of the first part 51. Therefore, when the optical element 33 is arranged on the extension of the second optical axis portion M2 of the second part 52, the projection optical system 3C is Y as compared with the case where the second length R1 is longer than the first length. It is possible to suppress the increase in the axial direction.

FIG. 19 is a diagram showing an MTF on the enlarged side of the projection optical system 3C. FIG. 20 is a spot diagram showing the state of light collection for each image height position. As shown in FIGS. 19 and 20, the projection optical system 3C has a high resolution.

(Example 4)
FIG. 21 is a ray diagram schematically showing the entire projection optical system 3D of the fourth embodiment. FIG. 22 is a ray diagram of the projection optical system 3D of the fourth embodiment. In FIGS. 21 and 22, the projection optical system 3D is viewed from above Y1. In FIGS. 21 and 22, the contours of the optical elements 33 constituting the second optical system 32 are omitted. FIG. 23 is an explanatory diagram schematically showing the optical axis of the projection optical system 3D from the reduction side image plane to the enlargement side image plane.

In the projection optical system 3D of this example, a deflection element 50 that refracts the first optical axis N1 is arranged in the middle of the first optical system 31 of the projection optical system 3B of the second embodiment. The optical elements 33 of the lenses L1 to L14 and the second optical system 32 are the same as those of the projection optical system 3B.

As shown in FIG. 21, the projection optical system 3D of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side. The first optical system 31 is a refraction optical system including a plurality of lenses L1 to L14 and a deflection element 50. As shown in FIG. 22, the first optical system 31 includes a cross dichroic prism 19 and 14 lenses L1 to L14. The lens L2 and the lens L3 are first bonded lenses L21 that are joined. The lens L4 and the lens L5 are a bonded second bonded lens L22. The lens L9 and the lens L10 are a bonded third junction lens L23. The lens L11 and the lens L12 are a fourth bonded lens L24 that is bonded.

The deflection element 50 is a plane mirror. As shown in FIGS. 10, 11, and 22, the deflection element 50 has a first air spacing having the widest distance between the upper surfaces of the shafts among a plurality of air gaps provided between adjacent lenses in the first optical system 31. It is placed in G2. The first air gap G2 is between the lens L10 and the lens L11, that is, between the third junction lens L23 and the fourth junction lens L24. The deflection element 50 is arranged at the first air gap G2 and bends the first optical axis N1 of the first optical system 31. In the first optical system 31, the first portion 51 located on the reduction side of the deflection element 50 includes lenses L1 to L10. In the first optical system 31, the second portion 52 located on the enlargement side of the deflection element 50 includes lenses L11 to L14.

Due to the arrangement of the deflection element 50, the first optical axis portion M1 which is the optical axis of the first part 51 and the second optical axis portion M2 which is the optical axis of the second part 52 intersect. In this example, the angle at which the first optical axis portion M1 and the second optical axis portion M2 intersect is 90 °. In other words, the deflection element 50 is arranged at an angle of 45 ° with respect to the first optical axis N1 of the first optical system 31 before the deflection element 50 is arranged. The first optical axis portion M1 extends in the Z-axis direction on the XZ plane, and the second optical axis portion M2 extends in the X-axis direction on the XZ plane. The deflection element 50 bends the light flux emitted from the first portion 51 in the first direction Z1 by 90 ° in the X-axis direction parallel to the screen S.

Here, the first part 51 has a positive power. Part 2 52 comprises negative power. Further, the first optical system 31 has positive power as a whole. As a result, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32 between the first optical system 31 and the second optical system 32.

The optical element 33 has a first transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in this order from the reduction side to the enlargement side. The first transmission surface 34 has a convex shape that protrudes toward the reduction side. The first reflecting surface 35 is a flat surface. The second reflecting surface 36 has a concave shape. The second transmission surface 27 has a convex shape that protrudes toward the enlarged side.

A light flux emitted from the first optical system 31 in the X-axis direction is incident on the first transmission surface 34. The first reflecting surface 35 bends the light flux passing through the first transmitting surface 34 by 90 ° in the second direction Z2 away from the screen S. The light flux reflected by the first reflecting surface 35 is reflected by the second reflecting surface 36 in the Y1 direction toward the first direction Z1. The luminous flux reflected by the second reflecting surface 36 and passing through the second transmitting surface 37 is emitted from the optical element 33 toward the first direction Z1 in the Y1 direction and reaches the screen S.

Here, as shown in FIG. 23, in the projection optical system 3D, the enlargement side image plane and the reduction side image plane are parallel. That is, the enlarged side reduced image plane on which the liquid crystal panel 18 forms the projected image is along the XY plane. The longitudinal direction of the liquid crystal panel 18, that is, the width direction W1 of the projected image extends in the X-axis direction. The lateral direction of the liquid crystal panel 18, that is, the height direction H1 of the projected image extends in the Y-axis direction. The screen S on which the final image is formed is along the XY plane. The longitudinal direction of the screen S, that is, the width direction W2 of the final image extends in the X-axis direction. The lateral direction of the screen S, that is, the height direction H2 of the final image extends in the Y-axis direction.

(Lens data)
The lens data of the projection optical system 3D is as follows.
Surface number Name rd nd vd Mode Y
Object surface 18 0 8.5 Refraction
1 19 0 35.95 1.51633 64.14 Refraction 12.573
2 0 5 Refraction 14.999
3 L01 29.33178 10.078656 1.442044 86.63 Refraction 16
4 -46.7571 0.1 Refraction 15.852
5 L02 148.79233 7.071831 1.772054 47.71 Refraction 14.902
6 L03 -26.54503 6.108227 2.0196 20.783 Refraction 14.521
7 -95.30317 0.1 Refraction 13.827
8 L04 57.12601 5.870101 1.494958 52.92 Refraction 12.989
9 L05 -24.31043 1 2.0508 26.942 Refraction 12.77
10 -887.31514 0.2 Refraction 12.691
11 L06 37.22942 2.436591 1.986125 16.48 Refraction 12.565
12 155.01669 2.483493 Refraction 12.414
13 L07 -45.82387 8.6095 1.526239 38.78 Refraction 12.314
14 -32.53128 9.5 Refraction 11.559
Aperture surface 0 0.1 Refraction 7.5
16 L08 -323.72495 2 2.0508 26.942 Refraction 7.5
17 42.89214 1.15812 Refraction 7.578
18 L09 1757.31503 4.943349 1.840029 18.61 Refraction 7.709
19 L10 -12.35292 2 2.0508 26.942 Refraction 7.982
20 -48.32828 28.476179 Refraction 8.812
21 51 0 -18 Reflection 21.055
22 L11 -45.45967 -15 1.686174 23.14 Refraction 19
23 L12 29.191 -12.671948 1.990031 16.9 Refraction 19.076
24 3485.13836 -4.481986 Refraction 21.906
* 25 L13 -105.64407 -6 1.531131 55.75 Refraction 22.487
* 26 519.77235 -24.526951 Refraction 23.721
* 27 L14 78.70625 -6 1.531131 55.75 Refraction 27.151
* 28 -66.20602 -2.620232 Refraction 30.053
* 29 34 -57.65154 -37 1.509398 56.47 Refraction 30.974
30 35 0 28 1.509398 56.47 Reflection 41.343
* 31 36 -17.73917 -40 1.509398 56.47 Reflection 20.636
* 32 37 60 -286 Refraction 37.407
Image plane S 0 0 Refraction 1897.748

The surface number 21 is a reflective surface of the deflection element 50. The surface number 21 decenter & bend is β = -45. The surface number 30, that is, the decenter & bend of the first reflecting surface 35 is α = 45. The aspherical coefficient of each aspherical surface is the same as that of the first embodiment. That is, the aspherical coefficients of the surface numbers 25 to 29 and the surface numbers 31 and 32 are the same as the aspherical coefficients of the surface numbers 24 to 28 and the surface numbers 30 and 31 of the first embodiment.

Further, as can be seen from the lens data, the first length R1 which is the total length of the first part 51 is longer than the second length R2 which is the total length of the second part 52. In other words, the second length R2, which is the total length of the second part 52, is shorter than the first length R1 which is the total length of the first part 51. The first length R1 and the second length R2 are the same as those in the third embodiment.

(Action effect)
The projection optical system 3C of this example can obtain the same effects as the projection optical system 3B of the second embodiment.

Further, in this example, a deflection element 50 that bends the first optical axis N1 of the first optical system 31 extending in the Z-axis direction in the X-axis direction is arranged. As a result, the first optical system 31 includes a second portion 52 extending in the X-axis direction and a first portion 51 extending in the Z-axis direction. Therefore, the projection optical system 3D of this example is larger in the Z-axis direction than the projection optical system 3B of the second embodiment, but can be miniaturized in the X-axis direction.

Further, in this example, the deflection element 50 is arranged in the first optical system 31 at the first air gap G2 where the distance between the upper surfaces of the shafts on the first optical axis N1 is the widest. Therefore, the deflection element 50 can be easily arranged. Further, even when the deflection element 50 is arranged, it is possible to prevent the first optical system 31 from becoming large.

Further, in this example, in the first optical system 31, the second length R2, which is the total length of the second part 52, is shorter than the first length R1 which is the total length of the first part 51. Therefore, when the optical element 33 is arranged on the extension of the second optical axis portion M2 of the second part 52, the projection optical system 3C is X as compared with the case where the second length R1 is longer than the first length. It is possible to suppress the increase in the axial direction.

FIG. 24 is a diagram showing an MTF on the enlarged side of the projection optical system 3D. FIG. 25 is a spot diagram showing the state of light collection for each image height position. As shown in FIGS. 24 and 25, the projection optical system 3D has a high resolution.

(Example 5)
FIG. 26 is a ray diagram schematically showing the entire projection optical system 3E of the fifth embodiment. FIG. 27 is a ray diagram of the projection optical system 3E of the fifth embodiment. In FIGS. 26 and 27, the projection optical system 3E is viewed from the Z-axis direction perpendicular to the screen S. In FIGS. 26 and 27, the contours of the optical elements 33 constituting the second optical system 32 are omitted. FIG. 28 is an explanatory diagram schematically showing the optical axis of the projection optical system 3E from the reduction side image plane to the enlargement side image plane.

In the projection optical system 3E of this example, a deflection element 50 that refracts the first optical axis N1 is arranged in the middle of the first optical system 31 of the projection optical system 3A of the first embodiment. Further, the refraction direction in which the first optical axis N1 is refracted by the deflection element 50 is set to a direction different from that of the projection optical system 3C of the third embodiment. The optical elements 33 of the lenses L1 to L14 and the second optical system 32 are the same as those of the projection optical system 3A.

As shown in FIG. 26, the projection optical system 3E of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side. The first optical system 31 is a refraction optical system including a plurality of lenses L1 to L14 and a deflection element 50. As shown in FIG. 27, the first optical system 31 has a cross dichroic prism 19 and 14 lenses L1 to L14. The lens L2 and the lens L3 are first bonded lenses L21 that are joined. The lens L4 and the lens L5 are a bonded second bonded lens L22. The lens L9 and the lens L10 are a bonded third junction lens L23. The lens L11 and the lens L12 are a fourth bonded lens L24 that is bonded.

The deflection element 50 is a plane mirror. As shown in FIG. 27, the deflection element 50 is arranged in the first air gap G1 having the widest distance between the upper surfaces of the shafts among the plurality of air gaps provided between the adjacent lenses in the first optical system 31. The first air gap G1 is between the lens L10 and the lens L11, that is, between the third junction lens L23 and the fourth junction lens L24. The deflection element 50 is arranged at the first air gap G1 and bends the first optical axis N1 of the first optical system 31. In the first optical system 31, the first portion 51 located on the reduction side of the deflection element 50 includes lenses L1 to L10. In the first optical system 31, the second portion 52 located on the enlargement side of the deflection element 50 includes lenses L11 to L14.

Due to the arrangement of the deflection element 50, the first optical axis portion M1 which is the optical axis of the first part 51 and the second optical axis portion M2 which is the optical axis of the second part 52 intersect. In this example, the angle at which the first optical axis portion M1 and the second optical axis portion M2 intersect is 90 °. The first optical axis portion M1 extends in the X-axis direction, and the second optical axis portion M2 extends in the Y-axis direction. The deflection element 50 bends the light flux emitted from the first portion 51 in the X-axis direction by 90 ° upward in Y1.

Here, the first part 51 has a positive power. Part 2 52 comprises negative power. Further, the first optical system 31 has positive power as a whole. As a result, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32 between the first optical system 31 and the second optical system 32.

The optical element 33 has a first transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in this order from the reduction side to the enlargement side. The first transmission surface 34 has a convex shape that protrudes toward the reduction side. The first reflecting surface 35 is a flat surface. The second reflecting surface 36 has a concave shape. The second transmission surface 27 has a convex shape that protrudes toward the enlarged side.

A light flux emitted from the first optical system 31 upward Y1 is incident on the first transmission surface 34. The first reflecting surface 35 bends the light flux passing through the first transmitting surface 34 by 90 ° in the second direction Z2 away from the screen S. The light flux reflected by the first reflecting surface 35 is reflected upward Y1 toward the first direction Z1 by the second reflecting surface 36. The luminous flux reflected by the second reflecting surface 36 and passing through the second transmitting surface 37 is emitted upward Y1 from the optical element 33 toward the first direction Z1 and reaches the screen S.

Here, as shown in FIG. 28, in the projection optical system 3E, the enlargement side image plane and the reduction side image plane intersect. That is, the enlarged side reduced image plane on which the liquid crystal panel 18 forms the projected image is along the YZ plane. The longitudinal direction of the liquid crystal panel 18, that is, the width direction W1 of the projected image extends in the Y-axis direction. The lateral direction of the liquid crystal panel 18, that is, the height direction H1 of the projected image extends in the Z-axis direction. The screen S on which the final image is formed is along the XY plane. The longitudinal direction of the screen S, that is, the width direction W2 of the final image extends in the X-axis direction. The lateral direction of the screen S, that is, the height direction H2 of the final image extends in the Y-axis direction.

(Lens data)
The lens data of the projection optical system 3E is as follows.
Surface number Name rd nd vd Mode Y
Object surface 18 0 8.5 Refraction
1 19 0 35.95 1.51633 64.14 Refraction 12.573
2 0 5 Refraction 14.999
3 L01 29.33178 10.078656 1.442044 86.63 Refraction 16
4 -46.7571 0.1 Refraction 15.852
5 L02 148.79233 7.071831 1.772054 47.71 Refraction 14.902
6 L03 -26.54503 6.108227 2.0196 20.783 Refraction 14.521
7 -95.30317 0.1 Refraction 13.827
8 L04 57.12601 5.870101 1.494958 52.92 Refraction 12.989
9 L05 -24.31043 1 2.0508 26.942 Refraction 12.77
10 -887.31514 0.2 Refraction 12.691
11 L06 37.22942 2.436591 1.986125 16.48 Refraction 12.565
12 155.01669 2.483493 Refraction 12.414
13 L07 -45.82387 8.6095 1.526239 38.78 Refraction 12.314
14 -32.53128 9.5 Refraction 11.559
Aperture surface 0 0.1 Refraction 7.5
16 L08 -323.72495 2 2.0508 26.942 Refraction 7.5
17 42.89214 1.15812 Refraction 7.578
18 L09 1757.31503 4.943349 1.840029 18.61 Refraction 7.709
19 L10 -12.35292 2 2.0508 26.942 Refraction 7.982
20 -48.32828 10.476179 Refraction 8.812
21 51 0 -18 Reflection 21.055
22 L11 -45.45967 -15 1.686174 23.14 Refraction 19
23 L12 29.191 -12.671948 1.990031 16.9 Refraction 19.076
24 3485.13836 -4.481986 Refraction 21.906
* 25 L13 -105.64407 -6 1.531131 55.75 Refraction 22.487
* 26 519.77235 -24.526951 Refraction 23.721
* 27 L14 78.70625 -6 1.531131 55.75 Refraction 27.151
* 28 -66.20602 -2.620232 Refraction 30.053
* 29 34 -57.65154 -47 1.509398 56.47 Refraction 30.974
30 35 0 18 1.509398 56.47 Reflection 41.343
* 31 36 -17.73917 -40 1.509398 56.47 Reflection 20.636
* 32 37 60 -286 Refraction 37.407
Image plane S 0 0 Refraction 1897.748
* 25 L13 -105.64407 -6 1.531131 55.75 Refraction 22.487
* 26 519.77235 -24.526951 Refraction 23.721
* 27 L14 78.70625 -6 1.531131 55.75 Refraction 27.151
* 28 -66.20602 -2.620232 Refraction 30.053
* 29 34 -57.65154 -47 1.509398 56.47 Refraction 30.974
30 35 0 18 1.509398 56.47 Reflection 41.343
* 31 36 -17.73917 -40 1.509398 56.47 Reflection 20.636
* 32 60 -286 Refraction 37.407
Image plane S 0 0 Refraction 1897.748

The surface number 21 is a reflective surface of the deflection element 50. The surface number 21 decenter & bend is β = 45. The surface number 30, that is, the decenter & bend of the first reflecting surface 35 is α = 45. The aspherical coefficient of each aspherical surface is the same as that of the first embodiment. That is, the aspherical coefficients of the surface numbers 25 to 29 and the surface numbers 31 and 32 are the same as the aspherical coefficients of the surface numbers 24 to 28 and the surface numbers 30 and 31 of the first embodiment.

Further, as can be seen from the lens data, the second length R2, which is the total length of the second part 52, is shorter than the first length R1 which is the total length of the first part 51. The first length R1 and the second length R2 are the same as those in the third embodiment.

(Action effect)
The projection optical 3E system of this example can obtain the same effects as the projection optical system C of the third embodiment.

Further, in this example, a deflection element 50 that bends the first optical axis N1 of the first optical system 31 extending in the X-axis direction upward Y1 is arranged. As a result, the first optical system 31 includes a second portion 52 extending in the Y-axis direction and a first portion 51 extending in the X-axis direction. Therefore, the projection optical system 3E of this example is larger in the X-axis direction than the projection optical system 3A of the first embodiment, but can be miniaturized in the Y-axis direction.

Further, in this example, the enlarged side reduced image plane on which the liquid crystal panel 18 forms the projected image is along the YZ plane. The longitudinal direction of the liquid crystal panel 18, that is, the width direction W1 of the projected image extends in the Y-axis direction. The lateral direction of the liquid crystal panel 18, that is, the height direction H1 of the projected image extends in the Z-axis direction. Here, the image forming portion 2 of the projector 1 may be formed in the longitudinal direction of the liquid crystal panel 18. In such a case, in this example, the footprint of the image forming unit 2 can be reduced when the projector 1 is viewed from above Y1.

FIG. 29 is a diagram showing an MTF on the enlarged side of the projection optical system 3E. FIG. 30 is a spot diagram showing the state of light collection for each image height position. As shown in FIGS. 29 and 30, the projection optical system 3E has a high resolution.

(Example 6)
FIG. 31 is a ray diagram schematically showing the entire projection optical system 3F of the sixth embodiment. FIG. 32 is a ray diagram of the projection optical system 3F of the sixth embodiment. In FIGS. 31 and 32, the projection optical system 3F is viewed from the Z-axis direction perpendicular to the screen S. In FIGS. 31 and 32, the contours of the optical elements 33 constituting the second optical system 32 are omitted. FIG. 33 is an explanatory diagram schematically showing the optical axis of the projection optical system 3F from the reduction side image plane to the enlargement side image plane.

In the projection optical system 3F of this example, a deflection element 50 that refracts the first optical axis N1 is arranged in the middle of the first optical system 31 of the projection optical system 3B of the second embodiment. Further, the refraction direction in which the first optical axis N1 is refracted by the deflection element 50 is set to a direction different from that of the projection optical system 3D of the fourth embodiment. The optical elements 33 of the lenses L1 to L14 and the second optical system 32 are the same as those of the projection optical system 3B.

As shown in FIG. 31, the projection optical system 3F of this example includes a first optical system 31 and a second optical system 32 in this order from the reduction side to the enlargement side. The first optical system 31 is a refraction optical system including a plurality of lenses L1 to L14 and a deflection element 50. As shown in FIG. 32, the first optical system 31 includes a cross dichroic prism 19 and 14 lenses L1 to L14. The lens L2 and the lens L3 are first bonded lenses L21 that are joined. The lens L4 and the lens L5 are a bonded second bonded lens L22. The lens L9 and the lens L10 are a bonded third junction lens L23. The lens L11 and the lens L12 are a fourth bonded lens L24 that is bonded.

The deflection element 50 is a plane mirror. As shown in FIGS. 11, 12, and 32, the deflection element 50 has a first air spacing having the widest distance between the upper surfaces of the shafts among a plurality of air gaps provided between adjacent lenses in the first optical system 31. It is placed in G2. The first air gap G2 is between the lens L10 and the lens L11, that is, between the third junction lens L23 and the fourth junction lens L24. The deflection element 50 is arranged at the first air gap G2 and bends the first optical axis N1 of the first optical system 31. In the first optical system 31, the first portion 51 located on the reduction side of the deflection element 50 includes lenses L1 to L10. In the first optical system 31, the second portion 52 located on the enlargement side of the deflection element 50 includes lenses L11 to L14.

Due to the arrangement of the deflection element 50, the first optical axis portion M1 which is the optical axis of the first part 51 and the second optical axis portion M2 which is the optical axis of the second part 52 intersect. In this example, the angle at which the first optical axis portion M1 and the second optical axis portion M2 intersect is 90 °. The first optical axis portion M1 extends in the Y-axis direction, and the second optical axis portion M2 extends in the X-axis direction. The deflection element 50 bends the light flux emitted from the first portion 51 upward Y1 by 90 ° in the X-axis direction along the screen S.

Here, the first part 51 has a positive power. Part 2 52 comprises negative power. Further, the first optical system 31 has positive power as a whole. As a result, the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system 32 between the first optical system 31 and the second optical system 32.

The optical element 33 has a first transmission surface 34, a first reflection surface 35, a second reflection surface 36, and a second transmission surface 37 in this order from the reduction side to the enlargement side. The first transmission surface 34 has a convex shape that protrudes toward the reduction side. The first reflecting surface 35 is a flat surface. The second reflecting surface 36 has a concave shape. The second transmission surface 27 has a convex shape that protrudes toward the enlarged side.

A light flux emitted from the first optical system 31 in the X-axis direction is incident on the first transmission surface 34. The first reflecting surface 35 bends the light flux passing through the first transmitting surface 34 by 90 ° in the second direction Z2 away from the screen S. The light flux reflected by the first reflecting surface 35 is reflected upward Y1 toward the first direction Z1 by the second reflecting surface 36. The luminous flux reflected by the second reflecting surface 36 and passing through the second transmitting surface 37 is emitted upward Y1 from the optical element 33 toward the first direction Z1 and reaches the screen S.

Here, as shown in FIG. 33, in the projection optical system 3F, the enlargement side image plane and the reduction side image plane intersect. That is, the enlarged side reduced image plane on which the liquid crystal panel 18 forms the projected image is along the XZ plane. The longitudinal direction of the liquid crystal panel 18, that is, the width direction W1 of the projected image extends in the Z-axis direction. The lateral direction of the liquid crystal panel 18, that is, the height direction H1 of the projected image extends in the X-axis direction. The screen S on which the final image is formed is along the XY plane. The longitudinal direction of the screen S, that is, the width direction W2 of the final image extends in the X-axis direction. The lateral direction of the screen S, that is, the height direction H2 of the final image extends in the Y-axis direction.

(Lens data)
The lens data of the projection optical system 3F is as follows.
Surface number Name rd nd vd Mode Y
Object surface 18 0 8.5 Refraction
1 19 0 35.95 1.51633 64.14 Refraction 12.573
2 0 5 Refraction 14.999
3 L01 29.33178 10.078656 1.442044 86.63 Refraction 16
4 -46.7571 0.1 Refraction 15.852
5 L02 148.79233 7.071831 1.772054 47.71 Refraction 14.902
6 L03 -26.54503 6.108227 2.0196 20.783 Refraction 14.521
7 -95.30317 0.1 Refraction 13.827
8 L04 57.12601 5.870101 1.494958 52.92 Refraction 12.989
9 L05 -24.31043 1 2.0508 26.942 Refraction 12.77
10 -887.31514 0.2 Refraction 12.691
11 L06 37.22942 2.436591 1.986125 16.48 Refraction 12.565
12 155.01669 2.483493 Refraction 12.414
13 L07 -45.82387 8.6095 1.526239 38.78 Refraction 12.314
14 -32.53128 9.5 Refraction 11.559
Aperture surface 0 0.1 Refraction 7.5
16 L08 -323.72495 2 2.0508 26.942 Refraction 7.5
17 42.89214 1.15812 Refraction 7.578
18 L09 1757.31503 4.943349 1.840029 18.61 Refraction 7.709
19 L10 -12.35292 2 2.0508 26.942 Refraction 7.982
20 -48.32828 10.476179 Refraction 8.812
21 51 0 -18 Reflection 13.186
22 L11 -45.45967 -15 1.686174 23.14 Refraction 19
23 L12 29.191 -12.671948 1.990031 16.9 Refraction 19.076
24 3485.13836 -4.481986 Refraction 21.906
* 25 L13 -105.64407 -6 1.531131 55.75 Refraction 22.487
* 26 519.77235 -24.526951 Refraction 23.721
* 27 L14 78.70625 -6 1.531131 55.75 Refraction 27.151
* 28 -66.20602 -2.620232 Refraction 30.053
* 29 34 -57.65154 -37 1.509398 56.47 Refraction 30.974
30 35 0 28 1.509398 56.47 Reflection 41.343
* 31 36 -17.73917 -40 1.509398 56.47 Reflection 20.636
* 32 37 60 -286 Refraction 37.407
Image plane S 0 0 Refraction 1897.748

The surface number 21 is a reflective surface of the deflection element 50. The surface number 21 decenter & bend is α = -45. The surface number 30, that is, the decenter & bend of the first reflecting surface 35 is α = 45. The aspherical coefficient of each aspherical surface is the same as that of the first embodiment. That is, the aspherical coefficients of the surface numbers 25 to 29 and the surface numbers 31 and 32 are the same as the aspherical coefficients of the surface numbers 24 to 28 and the surface numbers 30 and 31 of the first embodiment.

Further, as can be seen from the lens data, the second length R2, which is the total length of the second part 52, is shorter than the first length R1 which is the total length of the first part 51. The first length R1 and the second length R2 are the same as those in the third embodiment.

(Action effect)
The projection optical system 3F of this example can obtain the same effects as the projection optical system 3D of the fourth embodiment.

Further, in this example, a deflection element 50 that bends the first optical axis N1 of the first optical system 31 extending in the X-axis direction in the Y-axis direction is arranged. As a result, the first optical system 31 includes a second portion 52 extending in the X-axis direction and a first portion 51 extending in the Y-axis direction. Therefore, the projection optical system 3F of this example can be miniaturized in the X-axis direction as compared with the projection optical system 3B of the second embodiment.

FIG. 34 is a diagram showing an MTF on the enlarged side of the projection optical system 3F. FIG. 35 is a spot diagram showing the state of light collection for each image height position. As shown in FIGS. 34 and 35, the projection optical system 3F has a high resolution.

1 ... Projector, 2 ... Image forming unit, 3,3A, 3B, 3C, 3D, 3E, 3F ... Projection optical system, 4 ... Control unit, 6 ... Image processing unit, 7 ... Display drive unit, 10 ... Light source, 11 ... 1st integrator lens, 12 ... 2nd integrator lens, 13 ... Polarization conversion element, 14 ... Superimposition lens, 15 ... 1st dichroic mirror, 16 ... Reflection mirror, 17B ... Field lens, 17G ... Field lens, 17R ... Field lens , 18,18B, 18G, 18R ... LCD panel, 19 ... Cross dichroic prism, 21 ... 2nd dichroic mirror, 22 ... Relay lens, 23 ... Reflective mirror, 24 ... Relay lens, 25 ... Reflective mirror, 31 ... 1st optics System, 32 ... 2nd optical system, 33 ... Optical element, 34 ... 1st transmission surface, 35 ... 1st reflection surface, 36 ... Second reflection surface, 37 ... Second transmission surface, 40 ... Intermediate image, 50 ... Deflection Elements, 51 ... 1st part, 52 ... 2nd part, G1, G2 ... 1st air spacing, M1 ... 1st optical axis part, M2 ... 2nd optical axis part, N1 ... 1st optical axis, N2 ... 2nd Optical axis, N2 ... 2nd optical system, R1 ... 1st length of the 1st part, R2 ... 2nd length of the 2nd part.

Claims (22)

In a projection optical system including a first optical system and a second optical system in order from the reduction side to the enlargement side,
The second optical system includes an optical element having a first transmission surface, a first reflection surface, a second reflection surface, and a second transmission surface in this order from the reduction side to the expansion side.
The second reflective surface has a concave shape and has a concave shape.
A projection optical system characterized in that the first optical axis of the first optical system and the second optical axis of the second reflecting surface intersect. The first transmission surface and the first reflection surface are located on one side of the first optical axis.
The projection optical system according to claim 1, wherein the second reflecting surface is located on the opposite side of the first optical axis. The first transmission surface, the first reflection surface, and the second reflection surface are located on one side with respect to the second optical axis.
The projection optical system according to claim 1 or 2, wherein the second transmission surface is located on the opposite side of the second optical axis. Any one of claims 1 to 3, wherein the first transmitting surface, the second reflecting surface, and the second transmitting surface each have a shape that is rotationally symmetric with respect to the second optical axis. The projection optical system described in item 1. The projection according to any one of claims 1 to 4, wherein the first reflecting surface reflects a light flux passing through the first transmitting surface in a direction intersecting the first optical axis. Optical system. The projection optical system according to claim 5, wherein the first reflecting surface reflects a light flux passing through the first transmitting surface by 90 °. The projection optical system according to any one of claims 1 to 6, wherein the first optical system includes a plurality of lenses and a deflection element. The deflection element is arranged at the air interval having the widest distance between the upper surfaces of the shafts on the first optical axis among a plurality of air intervals provided between the adjacent lenses in the first optical system.
The projection according to claim 7, wherein the first optical system includes a first portion of the deflection element located on the reduction side and a second portion of the deflection element located on the enlargement side of the deflection element. Optical system. The first part has positive power and
The projection optical system according to claim 8, wherein the second part includes a negative power. The projection optical system according to claim 8 or 9, wherein the second length, which is the total length of the second part, is shorter than the first length, which is the total length of the first part. The projection optical system according to any one of claims 8 to 10, wherein the deflection element is a plane mirror. The projection optical system according to any one of claims 1 to 11, wherein the reduction side image plane intersects the enlargement side image plane. The projection optical system according to any one of claims 8 to 12, wherein the reduction side image plane is parallel to the enlargement side image plane. The projection optical system according to any one of claims 1 to 13, wherein the second transmission surface has a convex shape protruding toward the enlarged side. The projection optical system according to any one of claims 1 to 14, wherein the first transmission surface has a convex shape protruding toward the reduction side. The projection optical system according to any one of claims 1 to 15, wherein the second reflecting surface is an aspherical surface. The projection optical system according to any one of claims 1 to 16, wherein the second transmission surface is an aspherical surface. The projection optical system according to any one of claims 1 to 17, wherein the first transmission surface is an aspherical surface. The projection optical system according to any one of claims 1 to 18, wherein the first reflecting surface is a flat surface. Any of claims 1 to 19, wherein the distance between the main rays becomes narrower as the distance between the main rays approaches the second optical system between the first optical system and the second optical system. The projection optical system described in item 1. The projection optical system according to any one of claims 1 to 20, wherein an intermediate image is formed on the reduced side of the second reflecting surface. The projection optical system according to any one of claims 1 to 21 and
An image forming unit that forms a projected image on the reduced image plane of the projection optical system,
A projector characterized by having.

Images